professional studies slideshare(activity 2)
DESCRIPTION
life science (cell division, phptosythesis and human evolution)TRANSCRIPT
CHROMOSOMES Chromosomes form when the chromatin network in the nucleus of
the cell, coil up, shortens and thickens.
Each organism has a specific amount of chromosomes.
All humans have 46 chromosomes.
These chromosomes are arranged in identical pairs called homologous chromosome pairs –
Therefore humans have 23 homologous pairs of chromosomes.
These chromosomes is only visible during cell division processes.
One chromosome consist of 2 chromatids and one centromere that attach the chromatids together.
Each chromatid consist of genes which in turn consist of DNA.
CHROMOSOMESTRUCTURE
X and Y chromosomes: gonosomes/sex-chromosomes
Colored bands represents different genes
THE PHASES OF THE CELL CYCLE
The cell cycle includes the following phases:
Interphase (include G1- , S- [DNA synthesis] and G2 phase)
Prophase
Metaphase
Anaphase
Telophase
The result is 2 identical cells.
Why is Mitosis important?
Allow an organism to grow.
Repairs damaged cells/tissue.
Replace dead cells/tissue.
Reproduction in some simple organisms.
Where does Mitosis take place?
In all somatic cells (include all body cells and excludes the sex cells – sperm/egg cells)
The process of Mitosis.
CONSIST OF A FEW PHASES:
INTERPHASE
PROPHASE
METAPHASE
ANAPHASE
TELOPHASE
INTERPHASE
Cell builds up enough energy for division process.
DNA replication occurs
Cell look normal, like before division
PROPHASE
Nuclear envelope and nucleolus disappear.
Chromatin become more tightly coiled, and condenses into individual chromosomes. Chromosomes arrange randomly in the cell.
Centrioli move to opposite poles, with spindle fibers stretching between them.
METAPHASE
The centrioli reached the opposite poles with the spindle fibers in between.
The chromosomes arrange randomly on the equator, each single chromosome attaching to a separate spindle fiber by means of the centromere.
ANAPHASE
The spindle fibers pull tight.
The centromers attaching the chromatids of the chromosomes split in half.
Daughter chromosomes move to opposite poles.
EARLY TELOPHASE – KARYOKINESIS (DIVISION OF NUCLEUS
Daughter chromosomes reach poles.
Nuclear envelope surrounds chromosomes.
Nucleolus reappear at each pole.
Chromosomes become less condense forming chromatin.
Two identical nuclei has been formed
LATE TELOPHASE – CYTOKINESIS (DIVISION OF THE CYTOPLASM)
Invagination of the cytoplasm and plasma membrane occurs. (Cleavage furrow forms in animal cells and a cytoplasmic plate forms in plant cells)
Continues until the cell in divided into 2 separate cells. (Identical to one another and to the original cell)
MITOSIS PROCESS
UNIT TWOPHOTOSYNTHE
SIS
ZANELE PATIENCE NDEBELE201243373
Photosynthesis
A process that converts carbon dioxide into organic compounds
In other words:
The chemical process by which plants capture sunlight and use it to convert carbon dioxide and
water into food.
What uses photosynthesis??
Green plants
Flowers
Trees
Some algea
A few various forms of bacteria
**Mostly flowers and trees**
Most essential components of photosynthesis:
These include:
Direct sunlight
Water
Carbon dioxide
Chlorophyll
Who benefits from photosynthesis?
The plants/algea/bacteria
Other living beings such as animals
Even humans!!
Parts of Photosynth
esis
StomatesMicroscopic hole in the
stem and leaves of plants
This is where carbon dioxide enters the plant
At the same time,
water is entering the
plant through the
roots.
After being absorbed by the roots:The water travels all the way through the
stem to reach the leaves.
Chlorophyll
Contained in the plant
This is what makes the green color
What does chlorophyll do besides make the plant green??
When sunlight falls on the plant, the
chlorophyll captures the energy in it, and stores it for further
use.
This energy is
eventually used to
convert water into
hydrogen and
oxygen.
This is combined with the carbon dioxide to produce the
food for the plant
Hydrogen
The oxygen is let out through the stomates
OXYGEN
*Hydrogen is used to produce
food*Oxygen is let out as waste
product
Photosynthesis is
important in the
respiration of
humans and animalsWe use the oxygen produced by this
to fulfill our oxygen intake to live.
Proteins
Fats
Water soluble sugars
Photosynthesis also produces:
WE DEPEND ON PLANTS (OR ANIMALS
THAT FEED ON PLANTS) TO GET
THESE BECAUSE OUR BODIES CANNOT PRODUCE THESE
NUTRIENTS ON THEIR OWN
Photosynthesis plays a vital role in regulating the life
cycle on earth!
Sunlight, water, and the plants work together to supply the raw source of energy to us and help us breathe in oxygen to live
on.
Life without photosynthesis
would be impossible!!!
What is Evolution?
It is the gradual change from one form to another through a period of time.
Lamarck’s Theory
Acquired traits can be inherited
He proposed that:
Organisms change as their environment changes
Darwin’s Theory
Charles Darwin
Darwin’s Theory
Published “Origin of Species”
Traveled around the world in the Beagle
He proposed that:
Organisms produce more offsprings than the available resources can support
Organisms fight for limited resources like food, territory, and other necessities of life. Only those who survive can produce their own offspring
Variation exists within species. For example, some gorillas have longer arms than others.
Natural Selection - The environment selects organisms with beneficial traits.
Adaptation
Adaptation
Lamarck vs Darwin
Jean Baptist de Lamarck
Charles Darwin
1809 1859
French Naturalist English Naturalist
Acquired traits can be inherited by an organism
Organism adapts to changes in the environment. Only the fittest organisms survive through natural selection.
EVOLUTION
NATURAL SELECTION
ADAPTATION
Gradual change from one form to another through a period of
timeThe environment selects organisms with
beneficial traits
A form modified to fit a changed environment
Evidences of Evolution
Any preserved part or tissue of an organism that once lived.
FOSSIL
Types of Fossils
Casts
The mold is filled with another material
Molds
Hard body structures
Imprints
Feathers and leaves that
form impressions on
rocks
Petrified Fossils
When minerals replace the
hard parts of organisms
Biochemical Evidences
Indicate that some organisms have similar DNA sequences, which suggest common ancestry
DNA
VARIATION
Patterns of Evolution
Divergent
Related organisms
become very different
Convergent
Distantly related organisms
develop similar characteristics
Convergent Evolution
REFERENCES
Shyla Turner *** Instructional Technology TR 9:30-10:45***
Isabel V. Neri
Ziningi Mthembu (student at university of Johannesburg)